A non-profit organization is giving the nation and the world a chance to rekindle the spirit of unity and service that was seen in the aftermath of the terrorist attacks.

MyGoodDeed called on people to gather in Times Square on Thursday to pledge an act of service for what’s being called 9/11 Day. Hundreds lined-up to be the “I” on the “I will” sculpture in the middle of Square, CBS 2’s Cindy Hsu reported.

“We want to make this an annual tradition so that each 9/11 America stops and concentrates not so much on our differences, but on what we all have in common as people — the idea of helping one another,” co-founder David Paine said.

People were encouraged to share their pledge on Twitter, using the hashtag #911day, or on the website 911day.org.

Some of the pledges were projected on billboards in Times Square.

Aaron Scheinberg was a cadet at West Point on Sept. 11, 2001, and then served in Iraq. He told CBS 2’s Hsu how he’ll mark the anniversary.

“I personally pledge to challenge all post-9/11 veterans to continue their service after the military at home to better their communities across America,” Scheinberg said.

Ellen Bowen told Hsu the campaign is a chance to make sure her children never forget.

“My children were at the time just little kids, like 10 and 6, so every year we try to do a family project together. This year we’re planning on volunteering here in New York City on a special school project.”

MyGoodDeed started 9/11 Day in 2003 to encourage volunteerism and remember the victims of the terrorist attacks in a positive way. In 2009, the organization helped establish 9/11 as a National Day of Service and Remembrance.

Last year, for the 10-year anniversary of 9/11, more than 33 million people participated.

WATCH: 2012 9/11 Day Public Service Announcement

“Any good deed really does count and it’s in honor of all those who perished and the millions of people who rose in service in the aftermath of the 9/11 attacks,” said co-founder Jay Winuk, whose brother died in the 2001 attacks.

Paine said a simple good deed could go a long way.

“You don’t have to run into a burning building to be a hero in your community,” Paine said.